The discrepancy in minimum wages creates an uneven playing field for the nation's farmers because farm prices generally do not fluctuate on a regional basis, industry representatives say.

Northwest Christmas tree growers, for example, compete with growers in North Carolina, the country's second-largest producer after Oregon, which has a minimum wage of $6.15 an hour and is much closer to lucrative Eastern markets.

"Higher labor costs and higher transportation costs are all a part of a squeeze that we're caught in," said Beavercreek, Ore., Christmas tree farmer Stan Low.

Internationally, West Coast growers have other problems.

Bloomberg News reported that under Mexico's new minimum wage scales workers nearest the U.S. border will receive just under $5 a day. Mexico's minimum wage varies by region and costs of living.